The purpose of this study is the analysis of the elements that control adenovirus gene expression in lytically infected or in transformed cell cultures. Topics currently under investigation include: (a) the nature of early adenovirus functions that promote the growth of defective adeno-associated viruses, (B) molecular events that determine the host range of the hybrid virus Ad2 plus ND4 and (C) generation of adenovirus mutants which carry lesions in individual early gene regions. Besides standard procedures of molecular genetics ad biochemistry, techniques such as micro-injection of animal cells, electron microscopy and gene cloning in prokaryotic vectors, are used in these studies.